The Steam Radio would be with-in the Steam software, it works as long as the user has internet connection and is within Steam. It would be activated by clicking a button within the Steam library.

I got inspired for this idea when my friend decided to air music or audio from shows on his microphone, while we would comment or just listen while gaming. It was fun, and it didn't obstruct him from using his microphone and it didn't disrupt gameplay as we could hear each other clearly, even with the music. (Context:We were playing Left 4 Dead 2)

With many video game media provided coverage for events or game developers making videos to promote their game via videos, Steam Radio could air these thing should the developers and media want to reach out to a larger audience. Of course VALVe can't air music that doesn't belong to them, but they own a lot of music files from Left 4 Dead, Portal, Team Fortress and Half Life. They could approach other companies or vice versa, for usage of other audio or music used in games that they don't own.

User created shows like Freeman's Mind or The Underground, could also mean that users can create entertaining in-game audio commentaries or podcasts to be aired over the Steam Radio.

Alternatively, Steam Radio could be used as an ARG, when inside a specific games, when you reach certain points, the Steam Radio could have an audio file regarded the situation within the game. It could also serve as a commentary for developers (Yes, I am aware of the the developer commentary within Source Games) to communicate with players about how they designed a level.

My idea of a Steam Radio will be that it is not compulsory to have enabled, and it has to be manually enabled from the Steam Library (Or somewhere) in order for it to pop up and operate. It should continue operating even when switching between games.

Comments?

EDIT: After searching through the forums, I see that there's another Steam Radio suggestion, but my idea is for VALVe to create their own version of a Internet Radio, similiar to how games have in-game radios, but whereas VALVe's one with be within Steam, and can be head no matter what game or whether or not in-game. The other idea was to partner up with an actual radio station.